While migration in South Africa has been studied on a broad canvas, there have been few accounts of children's migration and the effects on living conditions and wellbeing. This article compares the access to services, housing and household amenities, and family characteristics of children born in the Greater Johannesburg metropolis with those of in-migrant children. The article also examines other indicators of child wellbeing related to parental care and schooling. In-migrant children, particularly children who have lived previously in rural areas and/or have recently migrated into the city, are significantly disadvantaged in comparison to long-term resident children in terms of parental education and occupation, housing type and ownership, access to electricity, refuse removal, water and sanitation. In-migrant children also live in households that are less likely to have amenities such as a refrigerator, television, washing machine, telephone and motor vehicle. In terms of child indicators, in-migrant children enjoy less frequent parental contact and are twice as likely to start school later than resident children. Whilst urbanisation to South Africa's metropolitan centres is generally associated with several widely recognised benefits, for children, these benefits may be tempered by the disadvantages of in-migrant families known to be associated with child wellbeing.